Technical Field
The present invention relates to the technical field of electrical engineering materials, and to an aluminum wire for power lines and electrical cables, and specifically, to a lightweight, high-conductivity, heat-resistant, and iron-containing aluminum wire used for overhead power supply and power transformation lines, and a preparation process thereof.
Description of Related Art
At present, heat-resistant wires used in power supply and power transformation lines in urban and rural areas of China have a long-term operating temperature that generally does not exceed 180° C. and electrical conductivity equal to or less than 61% IACS, causing higher line losses. According to the requirements on the development of national economy of China and the interconnection of energy sources, power transmission lines are to be developed into high-voltage, high-capacity and long-distance power transmission lines. In order to save insufficient corridor resources, reduce line construction costs, and reduce transmission line losses, it is strictly required that power transmission wires should not only have high electrical conductivity but also have satisfactory heat resistance and an excellent anti-sagging property.
In general, there is a tradeoff relationship between electrical conductivity and heat resistance and between electrical conductivity and strength. Micro-alloying is an effective way to improve heat resistance and strength of aluminum conductors, but it causes adverse impact to electrical conductivity. High purity aluminum with purity of 99.99% has electrical conductivity of 64.94% IACS at 20° C., density of 2.7 g/cm3, strength of only 80-100 MPa, and a recrystallization temperature of about 150° C. Alloy 6021 added with alloy elements such as 0.6-0.9 wt. % Mg, 0.5-0.9 wt. % Si, 0.5 wt. % Fe, 0.1 wt. % Cu and 0.1 wt. % Zn is commonly-used high-strength electrical engineering aluminum, and its tensile strength may be as high as 295-325 MPa, but its electrical conductivity is merely 52.5-55% IACS at 20° C. Therefore, development of low-cost wires with high electrical conductivity, satisfactory heat resistance, and high specific strength has become a difficult technical problem urgently to be addressed in the industry.
Chinese patent CN102230113A discloses a heat-resistant aluminum alloy conductor material and a preparation process thereof. An aluminum conductor material obtained by means of zirconium-erbium composite micro-alloying has electrical conductivity ranging from 59.5% IACS to 60.5% IACS, a long-term heat-resistance temperature of 180° C., and tensile strength lower than 160 MPa. Chinese patent CN102965550A discloses a high-strength, high-conductivity, and heat-resistant aluminum conductor material and a preparation process thereof. Al(Tm, Fe) phases in the shape of fine particles and Al3(Tm, Zr) shell-core structure phases that are dispersively distributed are obtained by means of zirconium-thulium-iron composite micro-alloying and isothermal precipitation and annealing processes, which substantially increase heat resistance and strength of aluminum conductor materials, and the prepared aluminum conductor material have a long-term heat-resistance temperature as high as 210° C., and tensile strength above 185 MPa, but its maximum electrical conductivity is only 60.8% IACS. Chinese patent CN102758107A discloses a high-strength, high-conductivity, and heat-resistant aluminum alloy wire and a preparation process thereof. Six alloy elements are added, including as many as three rare earth elements, and a zirconium element with a high content of 0.15%-0.60% is added. An annealing time of the alloy wire is as long as 30-50 hours, and the prepared aluminum conductor material can stand up to trial operation for 1 hour while being heated at 280° C. However, it has tensile strength lower than or equal to 160 MPa, electrical conductivity lower than or equal to 61.8% IACS, and a long-term heat-resistance temperature of only 180° C.